Cat c to d to c?

Im older but in shape , at the bottom of C middle to top when I race in D . 192 score puts me in D, race ranking is C ? Went to bed was a CAT C 424 , in the morning C C 525 ? Checked my segments and my race segment dropped from 1545 to 442 , why ? 128 races and now I’m confused . On Zwift since 12/23 hear all of the complaints and concerns with the scoring, not complaining or concerned , but confused on why my scores dropped like a rock . Not expecting to rise fast, nor drop fast .